The overall aim of this project is to establish the utility of Monodelphis domestica as a model for detecting and identifying genes that control lipemic response to diet. Specifically, we will: a. Perform segregation analyses to detect major genes that affect serum levels of very low plus low density lipoprotein (V + LDL) cholesterol and high density lipoprotein (HDL) cholesterol. b. Analyze data on the progeny of matings among high-responders and low responder lineages to test the following three hypotheses: (1) V + LDL cholesterol dietary response is controlled by two genes and one of these genes affects HDL cholesterol response. (2) A single gene affects distribution of cholesterol among LDL particle size subclasses. (3) The gene that affects cholesterol distribution among LDL subclasses is one of the genes that affects V + LDL cholesterol dietary response.